Small-Block Chevy Build - A Challenging Proposition

Building A Small-Block Chevy To Out-Power The LS7

To spin the camshaft, we veered from the antiquated "wet" timing-chain setup in favor of a much more advanced design, the beltdrive. Jesel has long set the standard in dry beltdrives, with kits that eliminate the timing chain and instead drive the cam with a belt located outside the crankcase. Here, it can be easily accessed for maintenance and to facilitate cam-timing changes. We also chose Jesel 1.6-ratio aluminum roller rocker arms for this engine, knowing that their shaft-mounted design, which places each pair of rockers on an individual shaft, is far superior to stud-mounted rockers and provides additional valvetrain stability.

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Internally, this engine will have to be able to survive the abuse we intend to hand it, on both the street and track, so only quality components would do. A quick check of Summit Racing's catalog and website was all it took to find the components we'd need for a tough bottom end. Starting with a Scat lightweight forged crankshaft, Scat I-beam connecting rods, and Clevite engine bearings, we added a set of Mahle forged pistons that will bring our compression ratio to 11:1, just like the LS7. To oil this small-block, we ordered a Stef's aluminum oil-pan kit that includes the pickup and pump, also from Summit Racing.

We've already taken the new parts to our local machine shop, Auto Performance Engines, to have the necessary operations performed. Once the machine work is done, we'll assemble this 427-inch combo and use the shop's Superflow dyno to test and tune the mill. How much power will we make? We hate to speculate before the engine is even running, but we'll be disappointed if we don't handily top the LS7's numbers with our "old school," first-generation SBC. Let us know if you think we have what it takes, and how much power you think we'll make, at www.vetteweb.com, and be sure to follow the rest of this series as we build, dyno, install, and test our LS7-killer small-block.

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Small-Block Chevy Build - A Challenging Proposition

We've been refurbishing and modifying Project C3 Triple-Ex for some time now, making the upgrades necessary for the installation of an engine with far more muscle than the current 350 is providing. This month, we'll outline our plans to repower this '71 Stingray.

Like many Corvettes, especially C3s, our Stingray came equipped with a 350ci V-8. Since the engine in our car isn't original, we have no incentive to keep it, so all we had to do was decide whether to swap in a big-block, an LS, or stay with a small-block.

We've spent a lot of time modifying our C3 project car, with all new suspension, brakes, interior, instrumentation, and a Tremec TKO five-speed transmission. Now it's time for the payoff: a powerful new engine.

Helping us decide on an engine for our Corvette was Editor Heath, who challenged us to build a first-generation small-block that would out-power an LS7. This is no small task, as the all-aluminum 427ci LS7 features CNC-ported heads, huge valves, a roller cam, and 11:1 compression.

Like many enthusiasts, we'd long since become accustomed to the moderate level of performance available from our Vette's stock engine.

Building a powerful small-block will definitely give our project car a shot in the arm, and perhaps a chance at a dragstrip rematch with Editor Heath.

Since we wanted to model our small-block after the LS7 in terms of displacement and weight, an aluminum block was our only choice. Dart Machinery makes some of the best aluminum blocks on the market, and had just what we needed for our LS7 killer SBC.

...billet main caps, a raised cam position, threaded core plugs, and optional 50mm cam journals and raised deck heights. This is a true race-style block, but it still retains full water jacketing and provisions for factory motor mounts, making it ideal for street use as well.

To top our block, we chose Dart's 23-degree PRO1 cylinder heads with 227cc intake runners. Like the LS7 cylinder heads, these Dart heads are made from cast aluminum and feature full CNC porting. Ours came fully assembled with roller valvesprings compatible with our Comp roller cam.

The Dart PRO1 CNC heads offer a great combustion chamber with plenty of quench area, along with large 2.08/1.60 valves. We'll still be giving up some intake-valve area to the LS7's 2.20-inch titanium piece, but we plan to more than make up for that with careful cam selection.

Knowing we'd need a stout rotating assembly to handle the planned output of this engine, we called Summit Racing Equipment and ordered a Scat lightweight forged crankshaft with a 4-inch stroke and 350-size main journals.

Scat 6-inch I-beam connecting rods will also be utilized in this normally aspirated combination.

We're using Mahle forged-aluminum pistons with an inverted dome for this application. We'll achieve our target compression ratio of 11:1 (or come very close to it) by removing material from the deck of the block and the deck surface of the head.

The Mahle pistons come as a kit, with high-performance piston rings and some of the narrowest pins we've seen, making them lightweight.

We'll be using a Comp Cams roller camshaft with just over 0.600-inch lift, along with a set of Comp's solid roller lifters. Solid-lifter camshafts offer more power and torque, and far better throttle response than hydraulic units. Additionally, we're out to prove that solid-lifter cams are feasible for street use.

To spin the camshaft, we'll be using a Jesel beltdrive system. Beltdrives eliminate the timing chain and gears, while also allowing precise cam-timing and -endplay adjustments. Though the LS engine is thought of as modern, it can't utilize this cutting-edge technology due to the oil pump's location.

We're using Jesel 1.6-ratio, shaft-mounted aluminum roller rocker arms for our application. The Jesel rockers bolt right onto our Dart heads, offering precise valvetrain stability even at much higher rpm than the 7,000 or so our small-block will see. If desired, Jesel offers rockers of up to 1.8-ratio for this application, and can accommodate valve lifts of more than 0.800 inch. Good luck achieving that kind of lift with any LS engine.

Since we're using the Jesel beltdrive, our application required a special damper. Fortunately, Summit Racing Equipment had the SFI-approved ATI damper we needed in stock and ready to ship.

Using Summit's website, we quickly found all the parts we needed, including our Clevite bearings, ARP head studs...

...and Fel-Pro gaskets.

Summit also had a complete oiling system to fit our Dart block and its Olds Rocket-style oil-pan rail. The kit from Stef's includes the aluminum, high-capacity oil pan with screen windage tray...

...as well as the oil pump and pickup. The latter item features a specially welded brace to prevent it from coming loose and dropping into the pan.

For induction, we're using a Dart aluminum, single-plane intake manifold that's specially designed and ported for the PRO1 CNC 227cc cylinder heads. We know this engine will need around 1,000 cfm or more of induction, so we'll experiment with several carburetors while it's on the dyno.

We've already taken our parts to our local machine shop, Auto Performance Engines, to begin the final machine work and engine assembly. Be sure to watch future issues of VETTE as we complete our LS7-killer small-block, dyno test the engine, and install it in Project C3 Triple-Ex.

We test some cost-effective parts for Small Block Chevys in a budget build with pistons, a camshaft, cylinder heads, a carburetor and a Zex nitrous system for Chevy 350 engines - Super Chevy Magazine » Read More